The patent document EP 0 081 464 A1 has already described a metallic bracelet formed of links hinged together the visible portions of which are constituted of decorative pieces in precious metal. Such decorative pieces cover over a core made up of plates linked together with the help of hinges.
According to this prior document, the decorative pieces are fixed to the main faces of the hinged plates by welding. Such fastening method presents difficulties, however. In particular, if the elements to be fixed onto the metallic core are of sintered hard metal or of ceramic, the welding provokes the appearance in the assembly of unacceptable mechanical stresses. Such stresses are due to the difference between the coefficient of thermal expansion of the hard material and of the machinable metal making up the core.
The patent document EP 0 015 242 B1 also describes a bracelet formed of links of which one of the faces is covered over by a thin protection part of sintered hard metal. The fastening of such protection part onto the body of the link is assured by two studs welded against one face of the protection part and which are retained by swaged rivet heads in holes traversing the body of the link.
According to this latter document, there is no part covering over the inner faces of the links. Consequently, when the bracelet is worn on the wrist, the hinged base body of the latter is found to be directly in contact with the arm of the user. Under such conditions, it is imperative that the bracelet core exhibit an inner surface which is quite smooth. In particular the hinges which form the bracelet links must not constitute projecting portions going beyond the inner surface of the bracelet between the link cores.
The dimension of the hinges of a link bracelet being incapable of reduction beyond a certain point without compromising the strength of the latter, the link cores must show a considerable thickness. It is for this reason that the links shown on the figures of the patent document EP-0 015 242 B1 are of relatively complex form. The obtaining of such thick links is relatively burdensome.
Bracelets obtained according to the document hereinabove further show the drawback of not including protection for the lateral portions of the links, the latter thus risking damage by a shock. Additionally, the link cores being partially visible and having a tint and texture different from that of the protection parts, the bracelet described cannot have the aspect of a bracelet the links of which are formed in one piece.
The German document DGM 8 904 193 describes a bracelet link the visible portions of which are entirely covered over by protection parts and which can thus present the appearance of a link formed in a single piece. Such bracelet link comprises initially a first protection part having substantially the form of a rectangular plate the upper face of which includes, proximate each of its ends, a raised zone constituting a shoulder and which forms a base on which studs are further secured. A link core constituted by a plate provided with hinges rests on such first protection part and said studs are engaged in piercings in the link core in order to assure the orientation. A second protection part forming a cap is driven onto the two shoulders of the first protection part. Such cap covers over and hides the link core as well as the two shoulders. We note that the cap, being driven onto the shoulders formed on the upper face of the base, its edges do not cover over the lateral faces of such first protection part. Such lateral faces thus remain visible when the bracelet is worn on the wrist.
This latter embodiment is furthermore unsuitable when the protection parts are of sintered hard metal. Effectively, elastic deformations cannot be required of a piece of sintered hard metal. In order to permit the cap to be held solidly secured onto the base by driving, it is thus necessary to produce parts which are dimensioned in an extremely precise manner. Since the parts shrink more than considerably in the course of sintering, it is necessary to have recourse to a subsequent machining which is extremely laborious.